An idea once considered radical—removing dams on rivers to restore fisheries—is becoming mainstream as scores of conservation efforts are paying off with restored river habitats and rejuvenated fisheries across North America.

In 1981, when the environmental group Earth First! wanted a publicity stunt to show how radical they were, they unfurled a giant black “crack” on the face of Arizona’s Glen Canyon Dam. Times have changed. Recently, a conservative Idaho Republican Congressman suggested he would seriously consider removing four dams on the Lower Snake River.

“I want the salmon back,” Rep. Mike Simpson said. “These are the most incredible creatures, I think, that God has created. It’s a cycle that God created.”

Why has dam removal gained popularity? Because it works. Decades of success removing old, obsolete dams and watching Mother Nature do the rest, have restored runs that were lost or suppressed for centuries.

New England states along the Delaware River system have been building dams since the 1700s. Those barriers created power and water for some of the earliest industries in the colonial Americas, providing slack water for shipping and turning water wheels for millstones in the days of George Washington.

But those dams also blocked migratory fish. Across the Eastern seaboard, sea-run fish like shad and Atlantic salmon disappeared. Removal, however, didn’t start as a conservation effort. As dams aged and industry changed, many fell into disrepair and became financial and safety liabilities. One unintended but significant side effect of their removal has been the impact on migratory fish. Shad runs in particular have bounced back.

“The responses from the fish are almost immediate. It’s awesome to watch. It’s happening all across the country,” said Chris Wood, president of Trout Unlimited. “I’m encouraged.”

According to the conservation group American Rivers, roughly 1,500 dams have been taken down in the past 100 years. At least 80 dams were breached in 2018 alone.

Those Eastern rivers are difficult to compare to the massive Columbia River Basin of the Pacific Northwest, historically one of the greatest producers of salmon and steelhead on Earth. The Columbia system has scores of dams, large and small. Salmon and steelhead runs have been declining steadily since the first barriers were built in the 1920s. The reasons are complex, but the dams play an outsized role.

At a conference in Boise this spring, Rep. Simpson noted that some $16 billion dollars have been spent trying to restore salmon and steelhead in the Columbia River Basin. Yet despite all that spending, the iconic fish continue to spiral toward extinction.

Last fall in Idaho, anglers, guides and rural river communities exploded in outrage when an lawsuit from environmental groups challenged Idaho’s steelhead fishery during a dramatically low return. Again in May, the Idaho Department of Fish & Game closed fishing in the entire Clearwater River Drainage, because of equally terrible Chinook salmon runs in that river system.

That dispute is a paperwork squabble compared to the root of the problem: four federal dams on the Lower Snake River that interfere with salmon runs both upstream and down. The stagnant reservoirs created by those dams create perfect habitat for juvenile salmon predators like smallmouth bass and northern pikeminnow, as well as warming the water to unsafe levels for returning adults—not to mention the thousands of fish killed in the turbines. Those four dams contribute almost nothing to the electrical grid and provide irrigation to only a handful of farmers. Their primary function is to allow shipping barges with agricultural produce to travel all the way from Lewiston, Idaho to the Pacific Ocean—a task that could be accomplished much more efficiently by rail.

“You cannot address the salmon issue without addressing dams. They are interwoven,” Rep. Simpson said.

In 2019, the Washington State Legislature passed a measure to study the impacts—both positive and negative—of removing the Lower Snake Dams.

Olympic National Park helped set the precedent for dam removal in Washington State. Starting in 2011, the National Park Service oversaw the removal of two dams on the Elwha River, the 105-foot Elwha Dam and the 200-foot Glines Canyon Dam. Biologists have already documented dramatic increases in Chinook salmon, sea-run bull trout and steelhead returns. Hundreds of tons of sediment trapped behind the dams for a century flushed downstream and rejuvenated the river delta.

“The Elwha looks more like an undammed river than a river choked with sediment,” said Andy Ritchie of the US.. Geological Survey. “Even without exceptional flows, a river can recover very rapidly after removing a dam or two.”

The Rogue River in Oregon has seen eight obsolete dams removed or modified over the past 10 years and some observers have noted a surge in salmon numbers due to the restoration of 150 miles of river habitat.

On the Oregon-California border, momentum is building to remove four hydroelectric dams on the giant Klamath River. Should those dams go, they would liberate some 400 miles of salmon and steelhead streams. The Klamath project still has to be approved by the Federal Energy Regulatory Commission, and several other regulatory hurdles remain before that project can take place. Under President Obama, the Department of the Interior actively supported removing the dams. Under President Trump, the DOI pulled its formal support and adopted a neutral stance.

Officials removed the 100-foot San Clemente Dam from the Carmel River near Big Sur, California in 2016, which had blocked that river since 1921. It’s said to be the largest dam removal in California history. One year after the deconstruction, seven steelhead returned to spawn in the Carmel. The next year, 29. So far this year, more than 130 steelhead have been documented.

“We don’t want to do the touchdown dance yet, but so far things are looking good,” Tommy Williams, a biologist with the National Oceanic and Atmospheric Administration, told the local newspaper. “It’s just amazing how fast these systems come back. Everything is playing out like we thought.”

For many of these rivers, it’s too early to gauge the impact of dam removal. Salmon have long life cycles—living and growing in oceans for several years before returning upstream, so assessing population trends can take decades. In addition, salmon face multiple threats—from pollution to warming oceans to degraded river habitat to skewed numbers of predators, both marine mammals and piscivorous fish. While improved access to spawning habitat is important, it’s not a silver bullet for all that ails salmon and steelhead.

The waters of central Idaho offer vast spawning habitat, and fish advocates see significant potential for restoring Idaho’s salmon and steelhead. These fish swim as far as to 900 miles and climb some 7,000 vertical feet from the ocean to spawn in central Idaho.

The Salmon and Clearwater rivers and their major forks and tributaries are in near-pristine condition, much of it protected as wilderness. Scientists say these waters will be increasingly important as the climate warms. The mountain snowpack in Idaho is reliable, and the high-elevation waters remain cold where other lower, more southernly rivers may grow too warm and dry for salmonids.

This is not to say that dams are always bad for native fish. In some places, such as Montana’s Flathead River system, the Hungry Horse Dam is the only thing that keeps unwelcome exotic species away from the protected, wilderness populations of bull trout and westslope cutthroat trout in the Bob Marshall Wilderness. Many other dams in the interior West provide cold, consistent water for trout populations that would otherwise not exist, like Wyoming’s North Platte or New Mexico’s San Juan.

Americans built dams for a lot of valid reasons. Dams control floods, provide reliability for irrigation and drinking water, allow barge traffic and generate electricity. The Lower Snake River dams in Idaho, for example, are popular with wheat farmers who use barges to ship their grain to ports downstream. Rep. Simpson acknowledged that dam removal isn’t simple and that many legitimate concerns have to be addressed and balanced.

TU’s Chris Wood agreed: “Some dams provide a lot of social uses and we will need to keep them,” he said. “But there are a lot of places where we can be asking the question. Are they worth it anymore?”

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